The present invention relates to a process for manufacturing a can lid which is lacquered on both sides and features at least one outlet which is covered by means of a sealed-on closure strip with polyamide sealing surface.
Lids for beverage cans are made of either aluminum, tin-plate or tin-free steel and are provided with one or more pouring outlets which are covered with a sealed-on closure strip. The metal can lids are normally coated with lacquer on both sides, for example, with a phenolic-epoxy resin coating. Known closure strips are made of a thin aluminum strip which is coated on the surface to be sealed with a thermoplastic material, for example, a polyamide.
It has been found that with metal can lids which are lacquer-coated on both sides and feature sealed-on closure strips of an aluminum-polyamide laminate, that the adhesive strength of the polyamide sealing layer on the lacquered lid surface is inadequate when used on cans having high internal pressures, for example, cans containing carbonated drinks stored for extended periods at temperatures above 30.degree. C.
In view of the foregoing it is the principal object of the present invention to develop a process as set forth above wherein the adhesive strength of the closure strip on the lid can be increased.